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  2. Mechanical calculator - Wikipedia

    en.wikipedia.org/wiki/Mechanical_calculator

    Mechanical calculator from 1914 An Addiator can be used for addition and subtraction. Two different classes of mechanisms had become established by this time, reciprocating and rotary. The former type of mechanism was operated typically by a limited-travel hand crank; some internal detailed operations took place on the pull, and others on the ...

  3. Pascal's calculator - Wikipedia

    en.wikipedia.org/wiki/Pascal's_calculator

    Pascal's calculator (also known as the arithmetic machine or Pascaline) is a mechanical calculator invented by Blaise Pascal in 1642. Pascal was led to develop a calculator by the laborious arithmetical calculations required by his father's work as the supervisor of taxes in Rouen. [2] He designed the machine to add and subtract two numbers ...

  4. Calculator - Wikipedia

    en.wikipedia.org/wiki/Calculator

    Pascal's calculator could add and subtract two numbers directly and thus, if the tedium could be borne, multiply and divide by repetition. Schickard's machine, constructed several decades earlier, used a clever set of mechanised multiplication tables to ease the process of multiplication and division with the adding machine as a means of ...

  5. Equation of time - Wikipedia

    en.wikipedia.org/wiki/Equation_of_time

    Its value is 0, 1, or 2 at different times of the year. Subtracting it leaves a small positive or negative fractional number of half turns, which is multiplied by 720, the number of minutes (12 hours) that the Earth takes to rotate one half turn relative to the Sun, to get the equation of time.

  6. Casio fx-39 - Wikipedia

    en.wikipedia.org/wiki/Casio_fx-39

    Time Arithmetic. The fx-39 has no real-time clock, but it can add and subtract hours, minutes and seconds displaying the result in sexagesimal . The degree symbol is represented by a small "zero" made from the upper four segments of the display (like an 8 without the bottom loop).

  7. Curta - Wikipedia

    en.wikipedia.org/wiki/Curta

    The nines' complement math breakthrough eliminated the significant mechanical complexity created when "borrowing" during subtraction. This drum was the key to miniaturizing the Curta. His work on the pocket calculator stopped in 1938 when the Nazis forced him and his company to concentrate on manufacturing precision instruments for the German ...

  8. Stepped reckoner - Wikipedia

    en.wikipedia.org/wiki/Stepped_reckoner

    The stepped reckoner or Leibniz calculator was a mechanical calculator invented by the German mathematician Gottfried Wilhelm Leibniz (started in 1673, when he presented a wooden model to the Royal Society of London [2] and completed in 1694). [1] The name comes from the translation of the German term for its operating mechanism, Staffelwalze ...

  9. Slide rule - Wikipedia

    en.wikipedia.org/wiki/Slide_rule

    Slide rule. Typical ten-inch (25 cm) student slide rule (Pickett N902-T simplex trig) A slide rule is a hand -operated mechanical calculator consisting of slidable rulers for evaluating mathematical operations such as multiplication, division, exponents, roots, logarithms, and trigonometry.